The invention relates to compositions that can be used as emulsifying and dispersing surfactants, and more particularly as additives for dispersing hydrates in oil effluents, and their preparation.
In U.S. Pat. No. 6,221,920, the Assignee described a process for the production of a composition consisting of a mixture containing at least amides, amines, ester-amides, ester-amines, salts of amines and mono-glycerides, formed from the monomeric, dimeric trimeric and/or tetrameric fatty acids contained in a polymerized polyunsaturated oil, this process comprising the transamdification and transesterification reaction of a thermally polymerized polyunsaturated oil, with at least one aminoalcohol, used in excess. In order that the final composition contains esteramide compounds, it was necessary to use aminoalcohols of which at least one amine function is primary or secondary. The aminoalcohols which are capable of being used were therefore, for example, monoethanolamine, monopropanolamine, monoisopropanolamine, 1-amino-butanol, 2-amino-1-butanol, N-methylethanolamine, N-butylethanolamine, pentanolamine, hexanolamine, cyclohexanolamine, polyalcoholamines or also polyalkoxyglycolamines, as well as aminated polyols such as diethanolamine, diisopropanolamine or trihydroxymethylaminomethane. Diethanolamine was preferably used.
The composition obtained could be used, without any purification, as an emulsifying and dispersing surfactant, as such or after dilution with various solvents, such as, for example, aromatic fractions, various alcohols or also with certain fatty acid esters.
It was indicated that the compositions thus defined were able to be used in a large number of applications, for example, as emulsifying agents allowing the formation of oil-in-water or water-in-oil emulsions, depending on the nature of the oil and the respective proportions of the two constituents (the hydrophilic constituent and the hydrophobic constituent). They could also be used as dispersing agents for solids or as foam stabilizers in a liquid or in an emulsion. A particular use which was indicated consisted of forming stable dispersions of ice in hydrocarbon media, for example, in light condensates of oil.
U.S. Pat. No. 5,958,844 describes another particular application of the compositions prepared according to the process of U.S. Pat. No. 6,221,920. This application consists of using them as dispersing additives for hydrates in suspension in fluids containing at least water, a gas and a liquid hydrocarbon (under conditions where hydrates may form from the water and gas), in a manner so as to facilitate transport of same.
It has now been realized that the effectiveness as dispersing additives for hydrates, of the compositions prepared as described in U.S. Pat. 6,221,920 varied according to the type of oil effluent considered and that, although it is excellent in certain effluents it can be less good in others.
Other compositions have now been found which can be advantageously used as emulsifying and dispersing surfactants and which have, as dispersing additives for hydrates, an improved effectiveness in certain oil effluents, in which the compositions prepared as described in U.S. Pat. No. 6,221,290 might be less effective.
Such compositions can be prepared by using aminoalcohols having at least one tertiary amine function instead of aminoalcohols having primary or secondary functions. These compositions do not include ester-amides.
The compositions according to the invention therefore contain at least compounds with ester and amine functions in the form of ester-amines, as well as the salts of amines, monoglycerides and diglycerides, these compounds being formed from monomeric, dimeric, trimeric and/or tetrameric fatty acids contained in a polymerized polyunsaturated, natural, vegetable or animal oil.
They can be obtained by a process which comprises the following stages:
a) use (or preparation) of a polymerized oil by polymerization of a polyunsaturated vegetable or animal oil;
b) optionally, treatment of said polymerized oil by entrainment with water vapor; and
c) reaction of the polymerized oil with an excess of at least one compound containing at least one hydroxyl function and at least one tertiary amine function, in the presence or not of a catalyst.
In order to prepare the compositions according to the invention, a commercial polymerized polyunsaturated oil can be used, such as the products known under the names xe2x80x9cstandoliexe2x80x9d, xe2x80x9cstand oilsxe2x80x9d or xe2x80x9cbodied oilsxe2x80x9d. In this case, stage (c) of the process is carried out directly, optionally preceded by a stage such as (b).
In a different manner, if in stage (a) one has to prepare the polymerized oil, one can start from any vegetable or animal oil having a degree of polyunsaturation sufficient to allow the polymerization by contact of the fatty chains containing diene or triene between themselves, as is the case, for example, for linoleic and linolenic acid. As examples the following oils can be mentioned: linseed, sunflower, safflower, china wood, grapeseed, soybean or corn, or certain fish oils, as well as any other oils having high levels of linoleic and/or linolenic acid.
Linseed oil is preferred in the invention. An approximate composition in fatty acids of linseed oil is as follows:
The polymerization of a polyunsaturated oil can be carried out according to any appropriate method, thermally or by catalytic route. The polymerization by essentially thermal route can be carried out by simple heating to approximately 300xc2x0 C. under nitrogen. The heating time then determines a viscosity gradient of the polymerized oil, which can reach, after a heating time for example of 20 hours or more, a dynamic viscosity of 65 Paxc2x7s at 20xc2x0 C.
The polymerization can also be carried out at 280-290xc2x0 C. under reduced pressure in the presence of anthraquinone or benzoquinone (see Nisshin Oils Mills, Yokohama, Japan, Nagakura and coll. (1975), 48(4), 217-22).
When the polymerized polyunsaturated oil used to produce the compositions according to the invention is prepared, in order to reduce the duration of the polymerization and therefore the risk of forming undesirable degradation products, provision can also be made to catalyze the polymerization of the starting polyunsaturated oil by metals, such as for example, zinc, lead, tin or copper in the form of nitrates, chlorides or stearates, or also manganese in the form of oxide or of a salt. In this respect, there can be mentioned for example the heating for 6 hours of the linseed oil with copper (II) nitrate in a proportion of 0.5 to 2% by weight relative to the starting oil described by Sil S. and Koley S. N., Department of Chemical Technology, Univ. of Calcutta (1987) 37(8), 15-22.
Among the metal catalysts used to reduce the duration of the reaction, a salt or dioxide of manganese MnO2 can be advantageously used, for example in a proportion of 0.5 to 2% by weight relative to the starting oil. Such catalysts can in fact be left in the final product without causing problems of toxicity or compatibility with the media in which the additive will be finally used.
In all cases, in order to be able to be used in the production process according to the invention, the polymerized oils advantageously have a dynamic viscosity at 20xc2x0 C. of 5 to 65 Paxc2x7s and preferably of 10 to 20 Paxc2x7s. They generally have an acid number of 8 to 20.
The composition of the oligomers of fatty acids contained in a polymerized linseed oil having a dynamic viscosity at 20xc2x0 C. of 65 Paxc2x7s is given hereafter, by way of example:
These values were obtained after methanolysis of the polymerized oil, and the separation of the methyl esters of the different fatty acids (monomers, dimers, trimers and higher oligomers) was achieved by gel-permeation chromatography (GPC). The acid number of the polymerized oil is equal to 16 mg of KOH/g.
The product of the polymerization reaction, after methanolysis, can be purified by distillation in order to eliminate from it the esters fraction corresponding to the monomeric fatty acids. A mixture is then obtained which contains approximately 1% of monomeric acids, approximately 75% of dimeric acids, approximately 19% of trimeric acids and approximately 5% of higher oligomers.
Moreover, it was noticed that it was possible to improve the properties of the compositions according to the invention by subjecting the polymerized oil, in an optional stage (b) which is carried out before the reaction with the aminoalcohol, to an operation of entraining with dry water vapor having the effect of deodorizing the polymerized oil and eliminating degradation products which could be present in the polymerized oils and pose problems vis-a-vis certain media in which the final compositions may be used.
In order to carry out this treatment, a stream of dry water vapor is passed over the polymerized oil to be treated, in a quantity of 5 to 30% by weight relative to the oil for example, at a temperature of 180 to 250xc2x0 C., under a vacuum of 7 to 2.5 kPa and for a period of 1 to 5 hours.
Stage (c) of the preparation process for the compositions according to the invention implements the reaction of the polymerized oil, optionally after treatment by entraining with water vapor, with an excess of at least one aminoalcohol containing at least one hydroxyl function and at least one tertiary amine function. Triethanolamine, for example can be used as the aminoalcohol.
This reaction can be carried out at a temperature of 100 to 200xc2x0 C. and preferably 110 to 160xc2x0 C., preferably without catalyst with elimination of the water vapor as it forms, either by using a third solvent in order to obtain an azeotrope, or by operating without solvent, but by elimination of the water by distillation under reduced pressure (see for example U.S. Pat. No. 2,089,212 and the article by Harry Kroll and Herbert Nadeau in J.A.O.C.S. 34, 323-326, June 1957). The reaction can also be catalyzed, which appreciably reduces its duration. As catalysts, alkaline alcoholates of lithium, sodium or potassium methylate or ethylate type are generally used. The reaction time is then 15 to 200 minutes; preferably, the reaction is stopped after 100 minutes.
The molar ratio of the aminoalcohol to the polymerized oil, expressed as the moles of fatty acids which it contains, is generally from 1/1 to 2/1, preferably, of the order of 1.5/1.
The product obtained by the process according to the invention consists of a composition mainly containing compounds with ester and amine functions, in particular in the form of ester-amines, as well as monoglycerides and diglycerides, formed from monomeric, dimeric, trimeric and/or tetrameric fatty acids, contained in the polymerized polyunsaturated oil. It can be used directly without any purification, either as such or after dilution in a solvent suitable for the emulsifying application chosen. The compatible solvents which may be used can be chosen from the aromatic solvents, such as for example toluene or xylenes, or the fractions of aromatic solvents, the esters of C1 to C8 monoalcohols and of the mixture of C6 to C22 fatty acids deriving from castor oil, the esters of C1 to C8 monoalcohols of hydroxylated C6 to C22 fatty acids obtained by chemical route and all esters produced by the opening of the epoxide bond of epoxidated mono-or polyunsaturated esters.
The compositions according to the invention are of particular use as dispersing additives for hydrates in oil effluents intended to reduce the tendency to agglomerate of said hydrates. In this use, these compositions are added to the fluid to be treated at concentrations ranging in general from 0.1 to 5% by weight, preferably 0.2 to 2% by weight relative to the water.
The entire disclosure of all applications, patents and publications, cited above and below, and of corresponding French application 99/06446, filed May 19, 1999 are hereby incorporated by reference.